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Harvey E. Jobson

Publications and source records attributed to Harvey E. Jobson.

24 records · Page 2Linked to original sources
USGS1978

Impact of flow regulation and power plant effluents on the flow and temperature regimes of the Chattahoochee River - Atlanta to Whitesburg, Georgia

A calibrated and verified transient flow temperature model was used to evaluate the effects of flow regulation and powerplant loadings on the natural temperature regime of the Chattahoochee River in northeast Georgia. Estimates were made of both instantaneous and average natural temperatures in the river during an eight-day period in August 1976. Differences between the computed average natural temperature and an independent estimate of natural temperature based on observed equilibrium temperatures were less than 0.5°C. The combined thermal effects of flow regulation and powerplant effluents resulted in mean daily river temperatures downstream of the powerplants about equal to or less than computed mean natural temperatures during the period of interest. An independent analysis of historical river and air-temperature data, although considerably less accurate than model computations, provided substantially the same result. The range and rates of change of computed natural diurnal temperature fluctuations were considerably less than those presently observed (1976) in the river. The models also were used to simulate summer river temperatures using estimated year 2000 flow conditions and meteorologic data collected during 1976. Except during periods of peak water-supply demand, differences between computed year 2000 river temperatures and observed present-day temperatures were less than 2°C.

Georgia↗
USGS1977

Stochastic analysis of particle movement over a dune bed

Stochastic models are available that can be used to predict the transport and dispersion of bed-material sediment particles in an alluvial channel. These models are based on the proposition that the movement of a single bed-material sediment particle consists of a series of steps of random length separated by rest periods of random duration and, therefore, application of the models requires a knowledge of the probability distributions of the step lengths, the rest periods, the elevation of particle deposition, and the elevation of particle erosion. The procedure was tested by determining distributions from bed profiles formed in a large laboratory flume with a coarse sand as the bed material. The elevation of particle deposition and the elevation of particle erosion can be considered to be identically distributed, and their distribution can be described by either a ' truncated Gaussian ' or a ' triangular ' density function. The conditional probability distribution of the rest period given the elevation of particle deposition closely followed the two-parameter gamma distribution. The conditional probability distribution of the step length given the elevation of particle erosion and the elevation of particle deposition also closely followed the two-parameter gamma density function. For a given flow, the scale and shape parameters describing the gamma probability distributions can be expressed as functions of bed-elevation. (Woodard-USGS)

Professional Paper↗
USGS1976

Comprehensive monitoring of meteorology, hydraulics, and thermal regime of the San Diego Aqueduct, California

Water temperature, as well as meteorologic and hydraulic variables which influence the energy budget of the San Diego Aqueduct in southern California, were continuously monitored for a 1-year period beginning July 24, 1973. Incoming solar and atmospheric radiation, windspeed and direction, water temperature, and wet- and dry-bulb air temperatures were recorded at 10-minute intervals at each end of the 26-km concrete-lined canal, while flow rates and stages were determined at hourly intervals for five locations. Although only daily averaged values are presented in this report, all information necessary for the use and interpretation of these data are presented. Windspeeds were minimum during the early morning hours and maximum during the late afternoon; however, they were variable spatially. On the other hand, incoming radiation and absolute vapor pressure varied little from point to point. (Woodard-USGS)

Open-File Report↗
USGS1975

Stochastic analysis of particle movement over a dune bed

Stochastic models are available that can be used to predict the transport and dispersion of bed-material sediment particles in an alluvial channel. These models are based on the proposition that the movement of a single bed-material sediment particle consists of a series of steps of random length separated by rest periods of random duration and, therefore, application of the models requires a knowledge of the probability distributions of the step lengths, the rest periods, the elevation of particle deposition, and the elevation of particle erosion. In the past, it has proven impossible to estimate these distributions except by use of tedious and time consuming single particle experiments.

Open-File Report↗
USGS1968

Vertical mass transfer in open channel flow

The vertical mass transfer coefficient and particle fall velocity were determined in an open channel shear flow. Three dispersants, dye, fine sand and medium sand, were used with each of three flow conditions. The dispersant was injected as a continuous line source across the channel and downstream concentration profiles were measured. From these profiles along with the measured velocity distribution both the vertical mass transfer coefficient and the local particle fall velocity were determined. The effects of secondary currents on the vertical mixing process were discussed. Data was taken and analyzed in such a way as to largely eliminate the effects of these currents on the measured values. A procedure was developed by which the local value of the fall velocity of sand sized particles could be determined in an open channel flow. The fall velocity of the particles in the turbulent flow was always greater than their fall velocity in quiescent water. Reynolds analogy between the transfer of momentum and marked fluid particles was further substantiated. The turbulent Schmidt number was shown to be approximately 1.03 for an open channel flow with a rough boundary. Eulerian turbulence measurements were not sufficient to predict the vertical transfer coefficient. Vertical mixing of sediment is due to three semi-independent processes. These processes are: secondary currents, diffusion due to tangential velocity fluctuations and diffusion due to the curvature of the fluid particle path lines. The diffusion coefficient due to tangential velocity fluctuations is approximately proportional to the transfer coefficient of marked fluid particles. The proportionality constant is less than or equal to 1.0 and decreases with increasing particle size. The diffusion coefficient due to the curvature of the fluid particle path lines is not related to the diffusion coefficient for marked fluid particles and increases with particle size, at least for sediment particles in the sand size range. The total sediment transfer coefficient is equal to the sum of the coefficient due to tangential velocity fluctuations and the coefficient due to the curvature of the fluid particle path lines. A numerical solution to the conservation of mass equation is given. The effects of the transfer coefficient, fall velocity and bed conditions on the predicted concentration profiles are illustrated.

Open-File Report↗